Apparatus for cracking hydrocarbons



Patented Sept. 10, 1935 I UNITED srA'rEs PATENT OF ICE APPARATUS FORCRACKING muocaanous Hermann Josef Schifller, Dusseldorf, Germany,assignor to the firm Vereinigte Stahlwerke Aktiengesellschaft,Dusseldorf, Germany No Drawing. Application August 19, 1931, Serial No.558,189. In Germany August 27, 1930 2 Claims. (Cl. 196-133) It has beenthe practice in processes for crackum for raising the resistance tocorrosion. The ing hydrocarbon liquids to employ high pressures.following steel alloys are given as samples comand temperatures with aview tosecure high bined according to the invention:

yields of the products of cracking and to ensure 5 economy.Thetemperatures employed in such v v 5 cracking processes are partlyabove the scaling ,SteelNo. Mn Cr Al Mo Ti limit of ordinary materialsemployed for those parts of cracking apparatus subjected to highpressures and temperatures, such as soft carbon- 4 )0 steels. There isthus a need for great resistance i 8;; 3 it 1 12 31% "(iii 10 todeterioration of the metal used forsuch parts 12 0,15 0,3 10 as 1.2 0,50.1 Be

of cracking apparatus.

Furthermore the material employed must be highly resistant to chemicals,as both crude oils When temperatures are employed which lie above I andtarry residues commonly contain sulphur the scaling limit it is notnecessary-to consider 15 compounds (in relatively large quantities) to vnot only a high hot tensile limit, but also to take which some steelsare highly sensitive.- into account the necessary resistance to seal- Inorder to reach the degree of resistance re- 'i 11? has been found y theapplicant h quired in the parts of apparatus that are subthe alloys thatsatisfy these requirements are jected to high pressures andtemperatures, althose whose chromium content lies between 5% go I loyedsteels are employed, among them being and 8%, and whose aluminiumcontent lies bechromium-nickel-steel. Steels containing nickel tween0.3% a a wh rmo e 00 have however proved to be sensitive to sulphur,tain'small quantities of silicon and molybdenum. and they exhibit'rnoreparticularly at high pres- Such a loy a resistant to s a p to aboutsures and temperatures, phenomena of brittle- 900 0., they have a highhot tensile limit, and g5 nesswhich may result in the fracture of thethey are highly resistant to sulphur. If the cracking tubes. Moreovernickel is known to process be carried out at temperatures whichliefavour the undue production of soft carbon inbelow the scaling limit thequantities of chrosuch and similar apparatus. mium used may be reducedto about 2%.

. Experiments carried out by theapplicant have Thus according to theinvention the cracking demonstrated that the parts of apparatus used 4of hydrocarbon liquids is efiected in an apparatus for crackinghydrocarbon liquids, when made of in which the parts subjected to hightemperasteel alloys are suitable when the metal contains tures andpressures are made of steel alloys which a substantial proportion ofchromium-andis subwhile they contain chromium do not contain stantiallyfree from nickel. The invention thus nickel. .comprises the use of ,suchsteel alloys for the The invention comprises the use of a process inpurpose. which the steel alloys employed for the parts of For thepurpose moreover the chromium con-'- the apparatus have a chromiumcontent up to 8% tent in such steel alloys may advantageously be and atthe most 13%. a as high as 7%, and in special cases even up Theinvention also comprises a small addition 0 to 13%. If still smallerquantities of aluminium of aluminium to the material so employed, and beadded to the chromium alloys the resistance the additions of othersubstances as hereinbefore to the action of sulphur and sulphurcompounds indicated, and an apparatus whose parts are made is increased.The aluminium content necessary of steel alloys having thecharacteristics indito produce this result lies between 0.8% and 4.0%.cated. A further improvement in the quality of the steel I wi beunderstood t the invention is is obtained by the addition 01' elements,such as broadly appli to Processes for crackinahysilicon, molybdenum,vanadium, titanium, beryldleeelben liquids, either in the liquid v p urlium, in quantities about 0.1% to 2%. Silicon phase, or partly in theliquid and partly in the may be added in order to improve themetallurgic -D Phase, it being understood t h m manufacture in regard tothe deoxydation and f the cracking or r a tubes. the re the degasifyingoi the steel. Molybdenum and or reaction, receiving, expansion or othervessels vanadium are able to raise the resistance to dethrough whichthhyd b n liquids flpo terioration in hot state. Titanium is added forpass at high pressures and high temperatures improving the structure ofthe grain and beryllior otherwise while subject to the conditions of theberyllium 0.1% to 2%, the balance substantially iron.

2. Apparatus for cracking liquid hydrocarbons comprising a part oftubular form, means for supplying hydrocarbons thereto, and impartingheat at cracking temperature, the said part consisting of a steel alloytree from nickel and containing chromium 5% to 13%, aluminum 0.3% to 4%,beryllium 0.1% to 2%, silicon 0.2% to 2%, molybdenum 0.3% to 2% and thebalance 10 substantially iron.

HERMANN VJOSEF SCHH'FLER.

